Abstract: The molecular mechanisms underlying premalignant gastrointestinal diseases, such as ulcerative colitis and Barrett's esophagus, remain unknown. For this reason, the expression of the protooncogene c-Ha-ras was studied in ulcerative colitis and Barrett's esophagus. Total cellular RNA was extracted from different regions of the gastrointestinal tract in these two diseases. Expression of c-Ha-ras was greater in proximal than in distal colon and undetectable in Barrett's esophagus. These regional differences in expression were not seen with the control gene beta-actin or with the protooncogenes c-myc and p53. In order to evaluate structural factors contributing to expression, amplification and methylation of c-Ha-ras DNA were studied in these tissues by Southern and slot blotting. No amplification of c-Ha-ras or six other protooncogenes was detected. These data suggest tissue-specific regulation of c-Ha-ras expression in the gastrointestinal tract in certain premalignant disease states.
Keywords: Adenomatous Polyposis Coli/*genetics; Barrett Esophagus/*genetics; Colitis, Ulcerative/*genetics; Colon/physiology; Gene Amplification; Humans; Intestinal Mucosa/pathology/*physiology; Methylation; Oncogene Protein p21(ras)/*genetics; Oncogene Proteins/genetics; Phosphoproteins/genetics; Precancerous Conditions/genetics; Proto-Oncogene Proteins/genetics; Proto-Oncogene Proteins c-myc; *Proto-Oncogenes; Tumor Suppressor Protein p53